Carboxylation of indene

ABSTRACT

METHOD OF CARBOXYLATING A COMPOUND OF THE GROUP OF R.C=CH,RCH2CN, INDENE, CYCLOPENADIENE OR FLUORENE, WHERE R IS HYDROCARBYL, COMPRISING CONTACTING SAID COMPOUND WITH CARBON DIOXIDE UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS IN THE PRESENCE OF A BASE OF THE FORMULA:   R1,(X-O-)BENZENE   WHERE X IS SODIUM OR POTASSIUM, R**1 IS HYDROGEN OR ALKYL AND SUBSEQUENTLY ACIDIFYING THE RESULTANT REACTION PRODUCT TO FORM THE CARBOXYLATED PRODUCT.

3,595,907 CARBOXYLATION OF INDENE Edwin L. Patmore, Fishlrill, andWilliam R. Siegart and Harry Chafetz, Poughlreepsie, N.Y., assignors toTexaco Inc., New York, N.Y. No Drawing. Filed Dec. 18, 1968, Ser. No.784,901 Int. Cl. C07c 51/14 US. Cl. 260-515 4 Claims ABSTRACT OF THEDISCLOSURE Method of carboxylating a compound of the group of R-CE-CH,RCH CN, indene, cyclopentadiene or fluorene, where R is hydrocarbyl,comprising contacting said compound with carbon dioxide undersubstantially anhydrous conditions in the presence of a base of theformula:

where X is sodium or potassium, R is hydrogen or alkyl and subsequentlyacidifying the resultant reaction product to form the carboxylatedproduct.

BACKGROUND OF INVENTION The subject invention is found in the field ofart relating to the introduction of a carboxylic acid group into organiccompounds.

In the past, in order to carboxylate starting compounds contemplatedherein by contacting with carbon dioxide, the contacting had to beaccomplished in the presence of expensive bases such as sodium,naphthalene, n-butyl lithium and sodium hydride. Due to the cost of thebase, the prior art methods of carboxylating starting reactants had onlylimited commercial prospects.

SUMMARY OF INVENTION We have discdvered a method of carboxylatingorganic compounds of the group of RCECH, RCH CN, indene, cyclopentadieneor fluorene, where R is alkyl, aryl, alkaryl and aralkyl of from 1 to 20carbons consisting essentially of contacting said organic compounds withcarbon dioxide under substantially anhydrous conditions in the presenceof a base of the formula:

where X is sodium or potassium and R is hydrogen or alkyl of from 1 to12 carbons, and subsequently acidifying the resultant reaction mixtureto recover the carboxylic acid. The discovery that the sodium andpotassium phenoxide salts facilitate the production of carboxylatedproducts in high yields has rendered a base catalyzed carboxylationprocess for the starting materials contemplated herein commerciallyfeasible since the phenoxide is many times less expensive than theprevious bases employed.

DETAILED DESCRIPTION OF THE INVENTION Specifically, the inventionrelates to contacting essentially in the absence of water an activehydrogen containing organic compound of the group R-CECH,

RCHgCN United States Patent 01' indene, cyclopentadiene or fluorene witha phenoxide of the formula:

Where R, R and X are as heretofore defined with carbon dioxidepreferably in excess and subsequently acidifying the resultant mixtureto respectively form carboxyl compounds of the group of R-CEC'COOH,

COOH

RCHON indene 3 carboxylic acid, tricyclo[5.2.1.0 ]deca-3,8-diene-4,9-dicarboxylic acid and tricyclo[5.2.1.0 ]deca-3,8-diene-5,S-dicarboxylic acid, or fiuorene-9-carboxylic acid. Thecarbonation advantageously takes place at a temperature between about 0and 150 C., preferably between about 25 and 50 C., under a carbondioxide pressure of between about 1 to 200 atmospheres, preferablybetween 1 and 25 atmospheres, utilizing a mole ratio of phenoxide toorganic compound of between about 1:1 and 20:1, preferably between 1:1and 5:1, and an excess of carbon dioxide. Advantageously, the reactionmixture is acidified desirably at a temperature between about 5 and 35C. to a pH of less than 6, preferably between about 1 and 3, to insurecomplete conversion of the intermediate alkali metal salt to the desiredacid product. Although the reaction may be conducted in the absence ofsolvent, an inert liquid solvent is preferably used in amounts ofbetween about 50 and wt. percent of the reaction mixture. The use ofsolvent is desirable in order for the production of maximum productyields.

By the term substantially anhydrous a water content of less than about0.5 wt. percent based on the reaction mixture during carbonation isintended.

Examples of the organic reactant compounds contemplated herein arephenylacetylene, benzyl cyanide, acetonitrile, hexanenitrile, acetylene,l-butyne and 1- hexyne.

Examples of the base constituents are potassium and sodium salts ofphenol, rnethylphenol, t-octylphenol, nonylphenol and dodecylphenol.

Specific examples of the acidifying acids contemplated herein are themineral acids such as hydrochloric acid, nitric acid, sulfuric acid andhydrobromic acid in aqueous concentrations ranging from 4 to 96 wt.percent.

Specific members of the inert liquid solvents contemplated herein areN,N-dimethylformamide, hexamethylphosphoramide, dimethyl sulfoxide,diphenyl sulfoxide, dimethyl sulfone and N,N-dimethylacetamide. Thesolvent during the carbon dioxide contact advantageously constitutesbetween about 50 and 90 wt. percent of the reaction mixture.

During the carbon dioxide contact the gas is normally passed through thereaction mixture in a liquid state. However, alternatively, the organicreaction mixture may be sprayed into an atmosphere of carbon dioxide orthe carbon dioxide may be passed over a solid or liquid surface which isdesirably continually changed by agitation in order to form a freshsurface for contact.

The carboxylic acid products are recovered from the reaction mixture bystandard means such as selective extraction, distillation, decantationand combinations thereof. Specific examples of the carboxylic acidproducts contemplated herein are indene-3-carboxylic acid, tricyclo-[5.2.1.0 ]deca-3,8-diene-4,9-dicarboxylic acid and tricyclo[5.2.l.0]deca-3,8-diene 5,5 dicarboxylic acid, phenylpropiolic acida-phenylcyanoacetic acid, cyanoacetic acid, u-cyanohexanoic acid,9-fluorene carboxylic acid, 2-butynoic acid, 2-propynoic acid and2-hexynoic acid.

The following examples further illustrate the invention but are not tobe considered as limitations thereof.

EXAMPLE I This example illustrates the preparation of indene-3-carboxylic acid from indene.

To a 3-necked round bottomed flask equipped with magnetic stirrer,thermometer, water cooled condenser and a gas sparger, the condenserconnected to a mercury bubbler to protect the system from atmosphere,3.5 grams of indene, 15.8 grams of potassium phenoxide, and 75 mls. ofdimethylformamide were charged. The resultant mixture had a watercontent of less than 0.5 wt. percent. An excess of dried carbon dioxidewas bubbled through the reaction mixture under atmospheric pressure overa period of 5 hours. At the inception of carbon dioxide introduction,the reaction mixture was at room temperature (about 26 C.). Thetemperature increased from room temperature to 45 C. within 5 minutesafter introduction. Within 8 minutes after introduction the temperaturedropped to 28 C. and thereafter remained during the entire reactionperiod between 26 and 28 C.

At the end of the five hour period the reaction mixture was poured intoa mixture of 80 mls. of concentrated hydrochloric acid and 100 grams ofice overlaid with 100 mls. of ether. The temperature of acidificationwas about 15 C. The layers were separated and the aqueous layerextracted with ether (5 x 100 mls.). The ether extracts were combinedwith the first organic layer. The combined ether organic layers wereextracted, wt. percent sodium bicarbonate (5 x 100 mls.) and the sodiumbicarbonate extracts were then acidified (to a pH of 1 to 3) with 6 MHCl while keeping the entire mixture cooled in an icewater bath. Thecombined acidified sodium bicarbonate extracts were then extracted intoether (5X 100 mls.), dried and the ether removed on a rotary evaporatorto give the crude carboxylated product. Recrystallization of the crudeproduct from benzene gave a yield of 1.79 grams of indene-3-carboxylicacid corresponding to a yield of 37.4 mole percent. The structure of theindene-3-carboxylic acid product was confirmed by its melting point of157 C. (lit. 158-160 C.) and its infrared and nuclear magnetic resonancespectra.

EXAMPLE II This is a description of the preparation of phenylpropiolicacid from phenylacetylene.

The carbon dioxide contact, acidification and recovery was the same asthat used in Example I with the following exceptions:

To the 3-necked flask there was charged 3.1 grams of phenylacetylene,15.8 grams potassium phenoxide and 75 mls. of dimethylformamide. Uponcharging of the first three reactants, the temperature rose from 27 to31 C. and the solution became dark brown. The water content therein wasless than 0.5 wt. percent. Then dried carbon dioxide in excess wasbubbled into the mixture and the temperature rose to 43 C. in 4 minutesand gradually returned to 32 C. at the end of the first hour. Thetemperature held at 31 C. for the next 2 hours. Total carbonation timewas 3 hours at a temperature in the range of 3l43 C.

The product after acidification and work-11p was 1.6 grams ofphenylpropiolic acid representing a yield of 37 mole percent having amelting point of 137-138 C. (lit. M.P. 137139 C.), a carbon content of73.9 wt. percent (74% calc.), a hydrogen content of 4.2 wt. percent(4.1% calc.) and an infrared spectrum identical to phenylpropiolic acid.

4 EXAMPLE HI This example illustrates the preparation ofa-phenylcyanoacetic acid from benzyl cyanide.

The procedure of Example I was essentially repeated with the followingexceptions:

To the reaction flask there was charged 3.5 grams of benzyl cyanide,15.8 grams potassium phenoxide, and 75 mls. of dimethylformamide. Theresultant mixture had a water content less than 0.5 wt. percent. Within3 minutes of charging the reactants to the flask the temperature rosefrom 31 to 45 C. and dropped to 32 C. over the next 19 minutes.Thereafter, the temperature during carbon dioxide bubbling remainedbetween 28 and 32 C. for the reaction period. The total carbonation timewas 4 hours. The temperature ranged in this 4 hour period between 28 and45 C.

After acidification and work-up a solid was recovered in an amount of2.7 grams and was determined to be a-phenylcyanoacetic acid in a yieldof 56 mole percent. The u-phenylcyanoacetic acid had a melting point of92.5-93.5 C. (lit. M.P. 92 C.) and infrared and nuclear magneticresonance spectra which confirmed it to be OL-Ph61'lYlCY3IlO3CClIlCacid. Elemental analysis found 67 wt. percent C (calc. 67), 4.3 wt.percent H (cal. 4.3) and 8.8 wt. percent N (calc. 8.7).

EXAMPLE IV This example illustrates the conversion of cyclopentadiene totricyclo[5.2.1.0 deca-3,8-diene-4,9-dicarboxylic acid better known asThieles acid and a minor amount of tricyclo[5.2.1.0]deca-3,8-diene-5,5-dicarboxylic acid.

The procedure employed was that of Example I with the followingexceptions:

There were introduced into the reaction flask 31.6 grams potassiumphenoxide, 4.0 grams cyclopentadiene and 125 mls. of dimethylformamide.The resultant mixture had a water content of less than 0.5 wt. percent.During carbon dioxide contact the temperature ranged from 33 to 47 C.over a period of 3 hours. The amount of carbon dioxide employed was inexcess of that required for the complete conversion of thecyclopentadiene reactant to the carboxylic acid derivative.

One product recovered after work-up was determined to be Thieles acid inan amount of 3.1 grams representing a 47 mole percent yield and having amelting point of 199201 C. (lit. M.P. 197199 C.). Its nuclear magneticresonance and infrared spectra confirmed it to be Thieles acid. A minoramount of tricyclo [5.2.1.0 ]deca- 3,8-diene-5,5-dicarboxylic acid wasalso found.

EXAMPLE V This example further illustrates the method of the inventionand is directed to a series of runs of the type found in Examples IIVexcept sodium phenoxide is substituted for potassium phenoxide.

The test data and results are reported below in Table I:

TABLE I Conditions of CO1 addition Product (mole Run CH Na, DMF,Reactant Temp, Time, percent No. g. mls. (g.) 0. hrs. yield) 27.8 ID(7.0) 32-60 5 IO (49) 13.9 75 BC (3.5) 33-48 6 PC (60) 13.9 75 PA (6.2)30-43 4 PP (58) 27.8 OF (4.0) 33-53 4 T (43) NOTE.DMF=Dimethylformamide;ID=indene; BC=Benzyl eyam'de; PA=Phenylacetylene; CP=Cyclopentadiene;IC=Indene-3 carboxylic acid; PC=a-Phenylcyanoacetie acid;PP=Phenylpropio1ic acid; T=Thieles acid.

EXAMPLE VI This example illustrates the criticality of the particularcombination of base and organic reactant in the production of carboxylicacids.

The procedure employed is essentially that described in Example I. Thetest data and results are reported below in Table II:

TABLE II Reaction conditions during CO2 addition Run DMF, Organic Temp,Time, COOH N 0. Base (mole) mls. reactant 0. hrs. prodhct AA... CnHsOK(0.1) 75 b-NT 2344 2.2 None. BB... OaHsOK (0.19; 100 CH 28-38 4 Do.CaH5OK(O12 75 FL 23-27 5 Do. DD.. IR-400 (0 04) 75 PA 27-30 2 Do. E NaOH(0.24) 75 p-NT 3240 4.8 Do. FF-.. CsHsONa (0.12) 100 ID 31-60 2 Do. GG..IR-400 (0.0 46-51 8 D0.

N g r iifi fi l olystyrene quaternary amine; p-NT=p.Nitrotolueue;CH=Oyclohexanone; FL=Fluorene; PA=Phenylacetylene; ID- IR=Indene.

As can be seen from the above table, substitution of organo and basereactants of a closely related nature for those contemplated herein failto produce a carboxylic acid derivative.

We claim:

1. A method of producing indene-3-carboxylic acid comprising contactingindene with carbon dioxide under substantially anhydrous conditions inthe presence of the base of the formula:

where X is sodium or potassium and R is hydrogen or alkyl of 1 to 12carbons, at a temperature between about 0 and 150 C. under a carbondioxide pressure between about 1 and 200 atmospheres utilizing a moleratio of base to organic compound of between about 1:1 and 20:1,subsequently acidifying the resultant reaction mixture to a pH of lessthan about 6 and recovering the carboxylic acid compound from theacidified mixture.

2. A method in accordance with claim 1 wherein said acidifying isconducted to a pH of between about 1 and 3.

3. A method in accordance with claim 2 wherein said acidifying isconducted with hydrochloric acid.

4. A method in accordance with claim 3 wherein said CO contacting isconducted in the presence of between about 50 and wt. percentdimethylformamide.

References Cited UNITED STATES PATENTS 3,346,625 10/ 1967 Fenton 260497JAMES A. PATTEN, Primary Examiner V. GARNER, Assistant Examiner US. Cl.X.R.

